From 9ef621d3be56e1188300476a8102ff54f7b6793f Mon Sep 17 00:00:00 2001 From: "Tan, Li" Date: Fri, 23 May 2008 14:54:09 +0800 Subject: [PATCH] KVM: Support mixed endian machines Currently kvmtrace is not portable. This will prevent from copying a trace file from big-endian target to little-endian workstation for analysis. In the patch, kernel outputs metadata containing a magic number to trace log, and changes 64-bit words to be u64 instead of a pair of u32s. Signed-off-by: Tan Li Acked-by: Jerone Young Acked-by: Hollis Blanchard Signed-off-by: Avi Kivity --- include/linux/kvm.h | 4 ++-- virt/kvm/kvm_trace.c | 18 ++++++++++++------ 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/include/linux/kvm.h b/include/linux/kvm.h index 1c908ac29c6c..0ea064cbfbc8 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -318,14 +318,14 @@ struct kvm_trace_rec { __u32 vcpu_id; union { struct { - __u32 cycle_lo, cycle_hi; + __u64 cycle_u64; __u32 extra_u32[KVM_TRC_EXTRA_MAX]; } cycle; struct { __u32 extra_u32[KVM_TRC_EXTRA_MAX]; } nocycle; } u; -}; +} __attribute__((packed)); #define KVMIO 0xAE diff --git a/virt/kvm/kvm_trace.c b/virt/kvm/kvm_trace.c index 0e495470788d..58141f31ea8f 100644 --- a/virt/kvm/kvm_trace.c +++ b/virt/kvm/kvm_trace.c @@ -72,11 +72,7 @@ static void kvm_add_trace(void *probe_private, void *call_data, rec.cycle_in = p->cycle_in; if (rec.cycle_in) { - u64 cycle = 0; - - cycle = get_cycles(); - rec.u.cycle.cycle_lo = (u32)cycle; - rec.u.cycle.cycle_hi = (u32)(cycle >> 32); + rec.u.cycle.cycle_u64 = get_cycles(); for (i = 0; i < rec.extra_u32; i++) rec.u.cycle.extra_u32[i] = va_arg(*args, u32); @@ -114,8 +110,18 @@ static int kvm_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, { struct kvm_trace *kt; - if (!relay_buf_full(buf)) + if (!relay_buf_full(buf)) { + if (!prev_subbuf) { + /* + * executed only once when the channel is opened + * save metadata as first record + */ + subbuf_start_reserve(buf, sizeof(u32)); + *(u32 *)subbuf = 0x12345678; + } + return 1; + } kt = buf->chan->private_data; atomic_inc(&kt->lost_records);